Incandescent lamp



March 1, i949; R. K. BRAuNsDoRr-'F 2,462,837

INCANDESGENT LAMP Filed oct. 8, 1945 96W s y Reginald K. raunsdorFF Patented Mar.l tIl, 1949 i mcANnEscEN'r LAMP `Reginald K. Braunsdorif, East Orange, N. J., as-

signor to Tung-Sol Lamp Works, Inc., Newark, N. J., a corporation of Delaware Application october s, 1945, serial N. 621.046

(ci. 17e-1s) 4 Claims.

This invention relates to incandescent electric lamps and particularly miniature lamps although the invention has utility in larger sized lamps.

One object of the invention is an incandescent electric lamp having a mount structure which is characterized by its durability and strength and by its elcient functioning as a getter for the lamp.

Further objects of the invention will hereinafter appear.

For a better understanding of the invention reference may be had to the accompanying drawings forming a part of this application, wherein Fig. 1 is a perspective view of an incandescent lamp embodying the invention;

Fig. 1A is an enlarged perspective view of a part thereof; and

Fig. 2 is a perspective view of a filament mount A according to another invention.

Ihe invention is illustrated as being embodied in a miniature incandescent lamp embodying an envelope l, a base i2, a press 6, a major filament I6 and a minor filament I8. The major lament I6 is carried by a pair of lead-in Wires I0 and I2 with the legs of the filament Welded to the embodiment of the upper righthand bends 24 of the support wires.

The minor filament I8 is carried by one support wire 20 in the form of an angle section welded to the support wire I and by a. second support wire 2| in the form of an angle section which is Welded to a lead-in wire I4.

The filament I6 is of conventional tungsten wire while the wire supports I0 and I2 are of dierent metals such, for example, as nickel. The conventional weld between the legs of the tungsten filament I6 and the support wires I0 and I2 is not truly a fusion of parts, the tungsten being merely pressed into place in the 'nickel lead with an overow of nickel metal surrounding or partially surrounding the filament leg and holding the leg in position mechanically.

In the gettering of incandescent lamps and the like the gettering material such, for example, as zirconium and other getters is introduced into the envelope or bulb to function merely as a getter without functioning in any manner to increase the strength and durability of the mount itself and in accordance with this invention the getter is introduced into the bulb or envelope in the form of a solid getter metal as, for example, zirconium and in amnner to reinforce and otherwise improvey the structure of the mount at the weld between the tungsten filament legs and the support wires as, for example, nickel wires. The introduction of the solid getter metal has the advantage over .the conventional powdered zirconium in that the solid zirconium is free from the vexplosive and burning character of the powder and need not be handled with the same care in the manufacture of the lamps.

In the embodiment of Figs. 1 and 1A the getter material is in the form of zirconium wire 23 incorporated in part in the welds between the legs of the filament I6 and the support wires and in the embodiment shown in Fig. 1A only one 0f the welds is thus formed although it is understood that both of such welds may be thus constructed.

The embodiment consists of a slip-coil 23 placed over the leg of lament in position at the point of weld. The parts to be welded are assembled in the usual manner between conventional welding tips (omitted for convenience). Welding current is controlled in the conventional manner. The use of zirconium slip-coil provides a protective layer to the filament leg and prevents crystallization of tungsten. In a conventional tungsten nickel weld a true weld is not attained,

the temperature reaching a value to cause the n nickel to flow and embed the filament leg mechanically. By applying a getter slip-coil. as for example zirconium, over the leg the upper welding electrode rests directly in contact with the outer surface of the zirconium coil, thereby introducing a layer of zirconium metal between the upper electrode and the tungsten leg. Thisacts as a heat radiator. Flow of metals during the welding current is then conned to the nickel wire in contact with the top electrode. Since there is an alloying between zirconium and nickel, this establishes an excellent fused weld, in the center of which is embedded the tungsten filament leg. During the welding the leg has been well protected from excess heat, thereby eliminating any tendency to become brittle at this point. The zirconium metal welds and flows nicely, as well as the nickel below, producing an excellent fused mass of flowed metal around the point of weld. Not only may the lamp thereby be eiliclently gettered but also the strength and endurance of the weld is substantially increased, with fewer imperfect welds and fewer rejections and premature filaments.

In the embodiment of Fig. 2 the solid getter metal forming a part of the weld between the filament leg and the support wire is in the form of a getter tab 22 as, for example, of solid zirconium. The zirconium tab 22 is applied over fthe filament leg weld to improve the strength'of weld. This is 'accomplished in part byl protecting against the heat of welding. The zirconium metal tab flows readily at welding temperature and establishes a zirconium-nickel alloy at this point, causing the filament leg to become embedded in the center section of fused parts. The

conventional tungsten nickel weld, as indicated above, is not truly an electrical fusion of parts, the tungsten being merely pressed into place in the nickel lead with an overflow of nickel metal surrounding or partly surrounding the filament leg and holding the leg in position mechanicallyg On subsequent burning of the filament there is the repeated expansion and contraction at this point with the result that the tungsten filament leg in the conventional weld may become loosened from its nickel base. The addition of a zirconium tab over this point prevents such loosening be-l cause the zirconium metal itself will tend to ow simultaneously with the flow of nickel and fuse into a common mass, probably a true alloy-1 ing of metals, in the center of which is held and maintained the leg of filament. 'Ihis provides positive mechanical holding of leg intrue welded position. The introduction of the zirconium `tab over the conventional parts separates the welding electrodes by this thickness of metal.

temperature of fusion. By `so protecting there Current i flow is established through the joint but the: tungsten filament leg does not attain the full is less tendency for the tungsten to become crystallized or brittle in this section. The zirconium tab acts asa radiation element and thereby protects leg of filament from excessive welding temperature.

In this embodiment also the tab or tabs 22 1 function both as efficient gettering means throughout the life of the lamp and as a means for strengthening and increasing the endurance of the welds and minimizing impairment of the tungsten filament legs.

While I have described solid zirconium as being the preferred getter-ing metal for use in the invention, it is understood that other gettering metals such, for example, as hafnium, columbium,

etc. may be used with certain of the advantages above enumerated with respect to zirconium presi ent in this structure.

This application is a continuation in part of s appncation, seriai No. 480,433 filed March 25, i 1943 abandoned October 11, 1945.

I claim:

1. In an incandescent electric lamp having a filament and supporting wires to which the legs of the filament are welded, means for gettering the llamp and improving and protecting at least one of the welds comprising a zirconium wire `coil about the filament leg and extending be- `yond the' weld, said coil portion in the vicinity of Yeach weld being alloyed with the supporting wire thereby providing a substantially lower resistance weld with the coil firmly bonded thereto, said coil being heated both by its close proximity to the filament and by absorption of heat in the weld to perform gettering action during the life of the lamp and maintaining the welded area at a lower temperature with a resultant decrease i in resistance by the absorption of heat therefrom.

2. In an incandescent electric lamp having a structure surrounding the lament leg and extending beyond -the weld, said structure in the vicinity of each weld being alloyed with the supporting wire thereby providing a substantially lower resistance weld with the structure firmly bonded thereto, said structure being heated both by its close proximity to the filament Iand by absorption of heat in the weld to perform gettering action during the life of the lamp and maintaining the welded area at a lowertemperature with a resultant decrease in resistance by the absorption of heat therefrom.

3. In an incandescent electric lamp having a filament and nickel supporting wires .to which the legs of the filament are welded, means for gettering the lamp and improving and protecting at least one of the welds comprising a, zirconium structure at and extending beyond the weld, said structure and the supprt wire in the vicinity of the weld being fused into a common mass with the filament leg embedded therein and with the supporting wire thereby providingla substantially lower resistance weld with the structure vfirmly bonded thereto, said structure `being heated both by its close proximity to the filament and by absorption of heat in the weld to perform gettering action during the life of the lamp and maintaining the welded area at a lower temperature with a resultant decrease in resistance by the absorption of heat therefrom.

4. In an incandescent electric lamp having a filament and supporting Wires :to which the legs of the filament are welded, means for gettering the lamp and improving and protecting at least one of the welds comprising a getter metal structure at and extending beyond the weld, said structure and the support wire in the vicinity of the weld being fused into a common mass with the filament leg embedded therein and with the supporting wire thereby providing a substantially lower resistance weld with the structure firmly bonded thereto, said structure being heated both by its close proximity to the lament and by absorption of heat in the weld to perform gettering action during the life of the lamp and maintaining the welded area ata lower temperature with a resultant decrease in resistance by the absorption of heat therefrom.

REGINALD K. BRAUNSDORFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number OTHER REFERENCES Great Britain May `6, 1940,'

"Fine Wires in the Electron Tube Industry," byv Geo. A. Esperson, Proceedings of I. R. E., v01 34, No. 3, Mar. 1946, 116-120. 

